JP2005138606A - Steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To quickly raise a temperature of a steering device in the steering device for steering a vehicle by steering a wheel in response to steering operation of a driver by using a motor in the vehicle. <P>SOLUTION: When the temperature T of a speed reducer in the steering device is lower than a threshold value Tth (S33) immediately after an ignition switch is turned ON by the driver in the vehicle (S31), the motor is utilized not as a driving source but as a heat source, i.e., a heater by feeding d-shaft current Id to a vector-controllable motor d (S34). Thereby, the decelerator is quickly heated without imparting motion to a member related to the motor. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a steering device that steers a vehicle by using a motor in the vehicle to steer wheels according to a steering operation of a driver, and more particularly to a technique for managing the temperature of the steering device. Is.

A steering apparatus that steers a vehicle by using a motor in the vehicle to steer wheels according to the steering operation of the driver is already known (see, for example, Patent Document 1).
This type of steering device has a characteristic that a steering characteristic realized by the steering device, that is, an input / output characteristic for the steering device depends on a temperature of the steering device. Here, the “steering characteristic” is defined as, for example, a driver's steering feeling reflecting the relationship between the driver's operation amount (for example, the steering wheel operation angle) and the operation reaction force, It may be defined as an input / output response characteristic of the drive system that reflects the relationship between the input and the wheel turning amount (ie, the output from the motor).

  Here, the reason why the steering characteristic depends on temperature is considered. For example, when the steering device uses a speed reducer to decelerate the operating speed of the motor and boost its driving force, the viscosity of the grease used for each sliding portion in the speed reducer increases at low temperatures. However, the resistance of the movable member to push away the grease and the lubrication resistance tend to increase. Therefore, it is considered that the transmission efficiency (for example, gear efficiency) of the speed reducer decreases at a low temperature, and thus dependence on temperature exists in the steering characteristics.

  By the way, this type of steering device is classified into several types depending on the application of the motor. For example, there is a first type steering device that uses a motor to generate an operation reaction force with respect to an operation of an operation member (for example, a steering wheel) operated by a driver for steering. There is also a second type of steering device that uses a motor to assist the driver in operating the operating member. There is also a third type of steering device that uses a motor to steer the wheels.

  In any type, the steering characteristics tend to be different between the low temperature and the normal temperature of the steering device. Specifically, in the first and second type steering devices, when the temperature is low, the actual value of the operation reaction force acting on the driver is reduced due to an increase in driving resistance of these steering devices, a decrease in transmission efficiency, and the like. Therefore, the driver feels a heavy steering feeling. Thus, in these steering devices, if the temperature rises, the steering characteristics change accordingly, which gives the driver an uncomfortable feeling that the steering characteristics are not stable.

  In the third type steering device, transmission efficiency (for example, gear transmission efficiency) is lower at a low temperature than at a normal temperature. Therefore, the amount of wheel breakage that responds to the same operation amount by the driver is reduced from that at normal temperature, and as a result, the followability of the wheel turning to the operation is reduced, and the driver feels a dull steering feeling. Become.

  Furthermore, the third type steering device may or may not use an operation reaction force motor for generating an operation reaction force. When the operation reaction force motor is not used, the steering force of the wheels is at least partially generated by the motor, and is common to the second type steering device. On the other hand, when the operation reaction force motor is used, it also serves as the first type steering device. In any case, like the first and second type steering devices, the third steering device tends to have a heavier steering feeling at low temperatures than at normal temperatures.

Patent Document 1 described above describes a conventional example of the second type steering device. In this conventional example, an input shaft is connected to a steering wheel as an operation member, and a motor is connected to the input shaft via a speed reducer. The motor is provided to assist the driver's steering operation, and the assist amount is changed based on the temperature of the reduction gear detected by the temperature sensor. The assist amount is changed so that the steering feeling is stabilized regardless of the temperature of the reduction gear.
JP 2002-53050 A

  In the above-described conventional example, the change in the steering characteristics due to the temperature change is suppressed only by the control of the assist amount. In the control of the assist amount, it is conceivable to control the steering characteristics by increasing the relationship (assist ratio) between the steering angle and the steering force at a low temperature from that at room temperature (for example, an electric power steering device). .

  However, even if an attempt is made to cancel the increase in the steering force generated at low temperatures by controlling the assist ratio, the increase in the steering force is accurately determined because the increase in the steering force changes according to the steering angle in the first place. It is difficult to cancel. For this reason, in assist control, it is difficult to accurately realize the same steering characteristics as those at normal temperature at low temperatures. Therefore, in this conventional example, it is difficult to sufficiently stabilize the steering characteristics.

  Against this background, the present invention uses a motor in a vehicle, and in a steering device that steers a vehicle by turning wheels in accordance with a steering operation of a driver, the temperature of the steering device is quick. The challenge was to make it rise.

  The following aspects are obtained by the present invention. Each aspect is divided into sections, each section is given a number, and is described in a form that cites other section numbers as necessary. This is to facilitate understanding of some of the technical features that the present invention can employ and combinations thereof, and the technical features that can be employed by the present invention and combinations thereof are limited to the following embodiments. Should not be interpreted. That is, although not described in the following embodiments, it should be construed that it is not impeded to appropriately extract and employ the technical features described in the present specification as the technical features of the present invention.

Further, describing each section in the form of quoting the numbers of the other sections does not necessarily prevent the technical features described in each section from being separated from the technical features described in the other sections. It should not be construed as meaning, but it should be construed that the technical features described in each section can be appropriately made independent depending on their properties.
(1) A steering device that steers a vehicle by turning wheels in accordance with a driver's steering operation in the vehicle,
A motor having a stator and a mover;
A moving member moved in relation to the steering;
A transmission device for transmitting the movement of the mover to the movement member;
A controller for controlling a supply current to the motor, and when a predetermined condition is satisfied, supplies a heat generation current for the motor to generate heat without the movement of the mover. Steering devices including things.

  In this steering apparatus, by supplying a heat generation current to the motor, the motor is used not as a drive source but as a heat source, that is, as a heater, so that the steering apparatus can be operated without giving movement to members related to the motor. Is heated.

  Therefore, according to this steering device, it is possible to raise the temperature of the steering device to an appropriate value in a short time compared to the case where the steering device is not actively heated. Furthermore, according to this steering device, it becomes possible to heat the steering device regardless of whether or not the driver performs a steering operation.

  When a current is supplied to the motor in order to drive the motor in response to a steering operation, the motor normally generates incidental heat. When the steering device is heated using such incidentally generated heat, if the steering operation is not performed, the motor does not generate heat, and thus the steering device is not heated. On the other hand, when the steering operation is performed, the motor generates heat and the steering device is heated. However, since the heat generation amount of the motor depends on the steering operation amount, the motor generates heat when the steering operation amount is small. The amount is also reduced, and the temperature rise of the steering device is also reduced.

  On the other hand, according to the steering device according to this section, the amount of heat generated by the motor can be managed regardless of the presence or absence of the steering operation and the amount of the steering operation, and the heating of the steering device is performed in a short time. It becomes easy.

As the “movement member” in this section, for example, there is an operation shaft (for example, a steering shaft) that is moved together with an operation member that is operated by a driver for steering. There is a steering rod (for example, a rack bar).
(2) The steering according to (1), wherein the condition includes a low-temperature condition that is established when a temperature of a heated portion to be heated by heat generation of the motor is equal to or lower than a set temperature. apparatus.

  In this steering device, when the temperature of the heated portion of the steering device is equal to or lower than the set temperature, the motor is actively caused to function as a heater, so that the temperature of the heated portion is quickly increased. .

Therefore, according to this steering device, it is easy to satisfactorily suppress the change in the steering characteristics when there is a possibility that the steering characteristics may be changed due to the low temperature of the heated portion. Therefore, it becomes easy to stabilize the steering characteristics regardless of the temperature of the heated portion.
(3) The steering according to (2), further including a temperature sensor that detects a temperature of the heated portion, wherein the controller determines whether or not the low-temperature condition is satisfied based on an output signal of the temperature sensor. apparatus.
(4) The driving resistance that the transmission device needs to beat in order to drive the transmission device is larger at the low temperature of the transmission device than at the high temperature, and the heated portion has its transmission The steering device according to (2) or (3), which is a device.

According to this steering device, when the heated portion is a transmission device, it becomes easy to stabilize the steering characteristics regardless of the temperature of the transmission device.
(5) The steering apparatus according to any one of (1) to (4), wherein the condition includes a travel start time satisfaction condition that is satisfied when a series of travels of the vehicle is started.

  In the steering device according to any one of the items (1) to (4), when it is necessary to heat the steering device by actively functioning the motor as a heater, the steering device is at a low temperature. Is the case. On the other hand, the temperature of the steering device is lowest at the start of a series of travels of the vehicle, and usually increases as travel continues.

Based on such knowledge, in the steering apparatus according to this section, the motor is positively caused to function as a heater when a series of running of the vehicle is started.
(6) Further, a travel start sensor for detecting the start of a series of travels of the vehicle is included, and the controller determines success or failure of the travel start time establishment condition based on an output signal of the travel start sensor (5) The steering device according to item.

As the “running start sensor” in this section, for example, a driving start switch (for example, for igniting an engine) operated by a driver to start driving of a power source (for example, an engine, a driving motor, etc.) of a vehicle. Ignition switch or key switch operated by the driver), a seating switch that detects that the driver is seated in the driver's seat of the vehicle, and a door lock release that detects that the driver has unlocked the driver's door There are switches.
(7) Further, an operation member operated by the driver is included, and the motor is configured to cause the motor to act on the driver via the operation member with an operation reaction force against the operation of the operation member by the driver. The steering apparatus according to any one of (1) to (6), including an operation reaction force motor to be driven.

  According to this steering device, the operation reaction force motor is positively functioned as a heater, for example, to stabilize the relationship between the operation amount of the operation member by the driver and the operation reaction force regardless of temperature changes. It becomes easy to make.

  The steering device according to this section can be implemented, for example, in such a manner that the operation reaction force motor is controlled in an open loop manner without feeding back the actual value of the operation reaction force. By the way, when controlling the operational reaction force motor by the open loop method, if the temperature of the steering device is lower than the normal temperature range, an increase in driving resistance of the steering device, a decrease in transmission efficiency, etc. Unless appropriate measures are taken, the operation reaction force becomes larger than the design value, which gives the driver a heavy steering feeling.

On the other hand, according to the steering device according to this section, since the operation reaction force motor can be actively functioned as a heater at a low temperature to heat the steering device, the motor control method is switched to the feedback method. Without increasing, it becomes easy to avoid an increase in the reaction force due to the temperature drop.
(8) Further, an operation member that is operated by a driver is included, and the motor includes an assisting motor that drives the moving member to assist the operation of the operation member by the driver. The steering device according to any one of items 1 to 3.

According to this steering apparatus, the assist motor actively functions as a heater, for example, to stabilize the relationship between the operation amount of the operation member by the driver and the operation reaction force regardless of the temperature change. Becomes easy.
(9) The steering apparatus according to any one of (1) to (8), wherein the motor includes a steering motor that drives the moving member to steer the wheel.

According to this steering device, by making the steering motor function positively as a heater, for example, the relationship between the operation amount of the operation member by the driver and the steering amount of the wheel can be stabilized regardless of the temperature change. It becomes easy to make it.
(10) In the motor, a permanent magnet is mounted on one of the stator and the mover, a coil is mounted on the other, and a d-axis is orthogonal to a direction parallel to the magnetization direction of the permanent magnet. Q direction is set in each direction,
The steering according to any one of items (1) to (9), wherein the heat generating current is a current that flows in the motor only in the d-axis direction out of the d-axis direction and the q-axis direction. apparatus.

According to this steering device, when a current is supplied to the motor in the direction of the d-axis, the motor is merely caused to function as a heater by paying attention to the property that the motor generates heat without generating a driving force.
(11) A drive current supply for supplying a drive current for driving the mover to the motor in parallel with the controller supplying the heat generation current to the motor during a steering operation of the driver. The steering device according to any one of (1) to (10), including a section.

According to this steering device, both the heating and the steering of the steering device can be realized in parallel by the same motor by causing the motor to function not only as a heater but also as a drive source.
(12) Further, an operation member operated by a driver is included, and when the driving current supply unit supplies the heat generation current to the motor, the driver does not supply the operation member with respect to the operation of the operation member. The steering apparatus according to item (11), wherein the drive current is changed so that an operation reaction force generated by the motor is reduced.

  The reaction force acting on the driver is a total of the driving resistance of the transmission device such as a reduction gear and the driving force of the motor. On the other hand, the direction in which the driving force of the motor changes the operation reaction force varies depending on the application.

  Specifically, when the motor is an assisting motor used for assisting the driver's operation, increasing the driving force of the motor means increasing the assist amount by the motor. This ultimately means that the reaction force acting on the driver is reduced.

  On the other hand, when the motor is an operation reaction force motor used to generate an operation reaction force, increasing the drive force of the motor means increasing the operation reaction force by the motor. This, in turn, means that the operation reaction force acting on the driver is increased.

  Therefore, when it is necessary to reduce the operation reaction force acting on the driver, it is desirable to increase the drive current for the assist motor, whereas for the operation reaction force motor, the drive current It is desirable to reduce

  In any case, in the steering apparatus according to this section, when it is necessary to cause the motor to function as a heater, that is, for example, when it is necessary to suppress a change in steering characteristics due to a temperature change. The motor can be made to function as a drive source, and the reaction force generated by the motor can be reduced as compared with the case where the drive current supplied to the motor that functions as the drive source does not require the motor to function as a heater. It is changed to the direction to do.

  As a result, according to this steering device, when it is necessary to cause the motor to function as a heater, the operation reaction force is also reduced by controlling the motor drive current, that is, optimizing the motor drive force.

Therefore, according to this steering device, it is possible to effectively suppress the change in the steering characteristics due to the temperature change by both the positive heat generation by the motor and the optimization of the motor driving force.
(13) The drive resistance that the transmission device needs to beat to drive the transmission device is greater at a low temperature of the transmission device than at a high temperature, and the motor is connected to the transmission device. A plurality of the motors are provided in association with each other, and the controller supplies the heat generating current to the motor closest to the transmission device among the plurality of motors according to the items (1) to (12). The steering device according to any one of the above.

  In the steering device according to the item (1), the transmission device has a larger driving resistance when the driving resistance is low and the motor is operatively associated with the transmission device. It is possible to implement in an embodiment.

  In this aspect, some of the plurality of motors may be closest to the transmission device. Unless such a motor is in a special environment, it is natural to consider it as the most efficient motor for heating the transfer device, considering heat transferability.

Based on such knowledge, in the steering device according to this section, the one closest to the transmission device among the plurality of motors is selected to function as a heater.
(14) The controller includes a travel start prohibiting unit that prohibits the start of travel of the vehicle until a temperature rise condition that is satisfied when the temperature of the heated part rises to a set temperature or higher (2 The steering device according to any one of items (13) to (13).

  According to this steering device, it is not necessary for the driver to perform a steering operation during a period in which the steering characteristics may be different from normal because the temperature of the heated part is lower than the normal temperature range. The driver does not have to feel uncomfortable that the steering characteristic changes.

  Hereinafter, some of more specific embodiments of the present invention will be described in detail with reference to the drawings.

  The steering apparatus according to the first embodiment of the present invention includes an operation unit 10 (see FIG. 1) operated by a vehicle driver and a steering unit 20 that steers left and right wheels 12 and 12 (see FIG. 2) of the vehicle. Are included.

  This steering device employs a steer-by-wire system in which left and right wheels 12 and 12 are electrically steered by a motor described later in accordance with an operation by a driver. In this steering apparatus, the operation unit 10 and the steered unit 20 are mechanically insulated from each other. In this steering apparatus, a plurality of motors are used as power sources.

  FIG. 1 systematically shows the mechanical configuration and electrical configuration of the operating unit 10 and FIG. 2 of the steered unit 20.

  As shown in FIG. 1, in the operation unit 10, a steering wheel 22 that is rotated by a driver is coaxially connected to an operation shaft 24 so as to be integrally rotatable. A rotational force of the motor A is applied to the operation shaft 24 in order to cause the steering wheel 22 to generate a pseudo operation reaction force. Therefore, the motor A is mechanically linked to the operation shaft 24 via a speed reducer (also a booster mechanism) 26.

  In the present embodiment, the motor A is configured as a DC motor as a brushless motor. As shown in FIG. 3, the motor A includes a stator 27 as a stator and a rotor 28 as a mover. The stator 27 is provided with a U-phase, V-phase and W-phase coil 29, and the rotor 28 is provided with a permanent magnet 30. The motor A is an example of a motor capable of vector-controlling the motor torque generated by the magnetic interaction between the stator 27 and the rotor 28.

  In this motor A, as shown in FIG. 3, the d-axis is in the direction parallel to the magnetization direction of the permanent magnet 30, and the q-axis is in the direction perpendicular to the direction (that is, the axis orthogonal to the magnetic flux generated from the permanent magnet 30). ) Is set for each. When a current is passed through the motor A in the d-axis direction, no motor torque is generated between the stator 27 and the rotor 28, and the electrical energy supplied to the coil 29 is converted into thermal energy. As a result, the motor A functions not only as a drive source but simply as a heater.

  On the other hand, when a current flows through the motor A in the q-axis direction, motor torque is generated between the stator 27 and the rotor 28, and the electric energy supplied to the coil 29 is not only thermal energy but also mechanical energy. Is also converted. Thereby, the motor A functions as a drive source.

  That is, in the present embodiment, the motor A constitutes an example of the “motor” in the above item (1), and the d-axis current Id that is a current flowing in the d-axis direction in the motor A is the “heating current” in the same term. The q-axis current that is the current that flows in the q-axis direction is an example of the “drive current” in the item (11).

  As shown in FIG. 1, in the present embodiment, the speed reducer 26 is configured such that the wheel gear 31 and the pinion gear 32 mesh non-coaxially. The wheel gear 31 is coaxially attached to the operation shaft 24 so as to be integrally rotatable, while the pinion gear 32 is coaxially attached to the rotor 33 of the motor A (see FIG. 3). That is, in the present embodiment, the operation shaft 24 constitutes an example of the “movement member” in the above item (1), and the speed reducer 26 constitutes an example of the “transmission device” in the same term.

  Further, an absolute angle sensor 34 that detects an absolute angle that is an absolute rotation angle of the operation shaft 24 is attached to the operation shaft 24. Here, the absolute angle is an angle that represents the rotation angle of the detected rotating body in consideration of the number of rotations of the detected rotating body, whereas the electrical angle is the rotation angle of the detected rotating body. The angle is expressed by ignoring the rotational speed of the detected rotating body.

  As shown in FIG. 1, the motor A and the absolute angle sensor 34 are connected to the controller 40. The motor A is connected to the controller 40 via the driver 36. A temperature sensor 41 is further connected to the controller 40. In order to detect the temperature of the speed reducer 26, the temperature sensor 41 is disposed at a position where the temperature sensor 41 comes into contact with the speed reducer 26 or a position where the temperature of the speed reducer 26 is so close that the temperature of the speed reducer 26 is efficiently transmitted.

  As shown in FIG. 4, the controller 40 is composed mainly of a computer 42. As is well known, the computer 42 includes a CPU 44, a ROM 46, and a RAM 48 connected to each other via a bus 50. The controller 40 is designed to control the rotation of the motor A by appropriately controlling the electric power supplied from the power source 51 via the driver 36 to the motor A according to the electrical angle of the motor A.

  As shown in FIG. 4, an ignition switch 51 a is connected to the controller 40. The ignition switch 51a is a key switch that is operated to ignite the engine of the vehicle so that the driver starts a series of travels of the vehicle. The ignition switch 51a is an example of an operation start switch that is an example of the “travel start sensor” in the above section (6).

  In addition, in place of or together with this ignition switch 51a, a seating switch for detecting that the driver is seated in the driver's seat, and that the driver has unlocked the driver's seat door outside the vehicle. It is possible to implement the present invention using a door lock release switch or the like that detects the above.

  As shown in FIG. 4, the ROM 46 stores various programs executed by the CPU 44. In these programs, an operation reaction force control program executed to control the operation reaction force by controlling the motor A and a steering characteristic (including a driver's steering feeling) of the steering device are stabilized. There is a steering characteristic stabilization program to be executed. The contents of the operation reaction force control program and the steering characteristic stabilization program are conceptually represented by flowcharts in FIGS. 5 and 6, respectively.

  FIG. 7 conceptually shows a portion of the controller 40 related to the control and driving of the motor A in a block diagram. As shown in the figure, the controller 40 includes a motor control unit 40a, a target operation reaction force torque calculation unit 40b, an operation reaction force control gain calculation unit 40c, and a d-axis current command value calculation unit 40d. .

  The motor control unit 40a includes information input from the target operation reaction force torque calculation unit 40b, operation reaction force control gain calculation unit 40c, and d-axis current command value calculation unit 40d, and information input from the absolute angle sensor 34. Based on this, it is set to perform a predetermined calculation in order to output a signal to the driver 36.

  Specifically, in this motor control unit 40a, in order to vector control the motor torque generated by the magnetic interaction between the coil 29 and the permanent magnet 30 in the motor A, the U phase, V phase and The current values Uo, Vo, and Wo to be output to each W-phase coil 29 are calculated using the d-axis current value Id and the q-axis current value Iq converted from them as a medium.

  More specifically, in the motor control unit 40a, the electrical angle detection unit 40e detects the electrical angle θe of the motor A based on the output signal of the absolute angle sensor 34. The current detection unit 40f detects current values Ui, Vi, and Wi that flow through the coils 29 of each phase of the motor A. Based on the detected electrical angle θe and the detected current values Ui, Vi, and Wi, the three-phase to two-phase conversion unit 40g converts the three-phase current values Ui, Vi, and Wi into two-phase current values. Conversion into a certain d-axis current value Id h and q-axis current value Iqh is performed.

  After the three-phase to two-phase conversion, the current control unit 40h receives the converted d-axis current value Idh and q-axis current value Iqh, and the q-axis current command value input from the q-axis current command value calculation unit 40i. A command signal is generated according to the PI control method based on Iq ref and the d-axis current command value Id ref input from the d-axis current command value calculation unit 40d. The generated command signal is input to the two-phase / three-phase converter 40j together with the electrical angle θe input from the electrical angle detector 40e.

  The two-phase / three-phase converter 40j is suitable for the d-axis current value Id h to approach the d-axis current command value Idref and the q-axis current value Iq h to approach the q-axis current command value Iq ref. The d-axis current value Id and the q-axis current value Iq are converted into three-phase current values Uo, Vo, Wo. Precisely, the two-phase to three-phase converter 40j converts the appropriate d-axis current value Id and q-axis current value Iq into the three-phase current values Uo, Vo, Wo through the three-phase coil 29. Three-phase voltage values Eu, Ev, Ew to be applied to the coils 29 of each phase for conversion are determined.

  After the two-phase to three-phase conversion, the PWM output unit 40k applies each voltage having the determined voltage values Eu, Ev, and Ew to the coil 29 of each phase through the driver 36, according to the PWM method. The value of each current flowing through the three-phase coil 29 is controlled. As a result, three-phase current values Uo, Vo, Wo are realized in the three-phase coil 29, respectively.

  The target operation reaction torque calculation unit 40b calculates a target value of the operation reaction torque to be applied to the driver based on the vehicle steering information such as the steering angular speed and the vehicle speed.

  The q-axis current command value calculation unit 40i affects the target value of the operation reaction force torque input from the target operation reaction force torque calculation unit 40b by multiplying the operation reaction force control gain α by multiplying the target value. The value Iq ref is calculated. The calculated value is supplied to the current control unit 40h. The operation reaction force control gain α used in the q-axis current command value calculation unit 40 i is calculated by the operation reaction force control gain calculation unit 40 c based on the temperature T of the speed reducer 26 detected by the temperature sensor 41.

  The d-axis current command value calculation unit 40d calculates a d-axis current command value Id ref based on the temperature T of the speed reducer 26 detected by the temperature sensor 41, and supplies the calculated value to the current control unit 40h. To do.

  Next, the operation reaction force control program will be described with reference to FIG.

  This operation reaction force control program is repeatedly executed while the power source 51 of the computer 42 is turned on. At the time of each execution, a signal is first input from the absolute angle sensor 34 in step S1 (hereinafter, simply represented by “S1”. The same applies to other steps). Next, in S2, the electrical angle θe of the motor A is calculated based on the input signal.

  That is, the portion of the computer 42 that executes S1 and S2 constitutes the electrical angle detector 40e in FIG.

  Subsequently, in S3 in FIG. 5, information necessary for controlling the operation reaction force is input. Such necessary information includes, for example, steering angular speed, vehicle speed, and the like. The steering angular velocity can be calculated based on the output signal of the absolute angle sensor 34, for example.

  Thereafter, in S4, based on the input necessary information, a torque to be applied to the steering wheel 22, that is, a target operation reaction torque is calculated.

  That is, the portion of the computer 42 that executes S3 and S4 constitutes the target operation reaction torque calculation unit 40b in FIG.

  Subsequently, in S5 in FIG. 5, the d-axis current command value Id ref is determined based on the calculated target reaction force torque and the operation reaction force control gain α. The operation reaction force control gain α is determined by executing the steering characteristic stabilization program shown in FIG. That is, the portion of the computer 42 that executes S5 constitutes the q-axis current command value calculation unit 40i in FIG.

  Thereafter, in S6 in FIG. 5, the current to be supplied to the motor A is calculated. Specifically, the detected electrical angle θe, the determined q-axis current command value Iq ref, the actual current values Ui, Vi, and Wi of the coils 29 of each phase of the motor A are shown in FIG. Based on the d-axis current command value Id ref determined by executing the steering characteristic stabilization program, current values Uo, Vo, Wo to be realized in the coils 29 of the respective phases of the motor A are calculated according to the principle of vector control. Is done.

  That is, the portion of the computer 42 that executes S6 corresponds to the current detection unit 40f, the three-phase to two-phase conversion unit 40g, the current control unit 40h, and the two-phase to three-phase conversion unit 40j in FIG.

  Thereafter, in S7 in FIG. 5, a signal is supplied from the controller 40 to the driver 36 so that a current having the same magnitude as the calculated current value is supplied from the power source 51 to the coil 29 of each phase of the motor A. Thus, the motor A is driven. That is, the part of the computer 42 that executes S7 corresponds to the PWM output unit 40k in FIG.

  Thus, one execution of the operation reaction force control program is completed.

  Next, the steering characteristic stabilization program will be described with reference to FIG.

  This steering characteristic stabilization program is also repeatedly executed while the power source 51 of the computer 42 is turned on. When executing each time, first, in S31, it is determined whether or not it is immediately after the ignition switch 51a is turned ON by the driver. If it is assumed that it is immediately after being operated to be ON this time, the determination is YES, and the temperature T of the speed reducer 26 is detected by the temperature sensor 41 in S32.

  Subsequently, in S33, it is determined whether or not the detected temperature T is lower than a threshold value Tth. This time, if it is assumed that the temperature T of the speed reducer 26 is low immediately after the start of a series of travels of the vehicle, the determination is YES.

  Thereafter, in S34, the d-axis current command value Id ref is determined based on the detected value of the temperature T. In the present embodiment, for example, as shown by a graph in FIG. 8, the relationship between the temperature T and the d-axis current command value Id ref is stored in the ROM 46, and the d-axis corresponding to the current temperature T according to the relationship. A current command value Id ref is determined.

  In the present embodiment, as shown in FIG. 8, in the first low temperature region where the temperature T is considerably lower than the threshold value Tth, the d-axis current command value Id ref is maintained at the maximum value. Heat generation, and hence the reduction gear 26 is heated rapidly. In the second low temperature region that follows the first low temperature region and is slightly lower than the threshold value Tth, the d-axis current command value Id ref is decreased as the temperature T rises. The above heating is avoided.

  As a result of the d-axis current command value Id ref being controlled in this way, the operation reaction force acting on the driver is limited to the same magnitude as that in the normal temperature region, although it is in the low temperature region. As a result, the operation reaction force does not greatly vary depending on the temperature T of the speed reducer 26.

  That is, the portion of the computer 42 that executes S34 constitutes the d-axis current command value calculation unit 40d in FIG.

  When the execution of S34 in FIG. 6 ends, in S35, the command value α ref of the operation reaction force control gain α is determined. In the present embodiment, for example, as shown by a graph in FIG. 9, the relationship between the temperature T and the command value α ref is stored in the ROM 46, and the command value α ref corresponding to the current temperature T is determined according to the relationship. It is determined.

  In the present embodiment, as shown in FIG. 9, in the low temperature region where the temperature T is lower than the threshold value Tth, the command value α ref is set to a value smaller than 1, and the variable value increases as the temperature T increases. Thus, the component that contributes to the driving force of the motor A among the operating reaction forces acting on the driver is made smaller than in the normal temperature range where the temperature T is equal to or higher than the threshold value Tth.

  Limiting the command value α ref to a value smaller than 1 means limiting the q-axis current command value Iq ref to a value smaller than normal, and thus contributes to the generation of the driving force of the motor A, that is, the operation reaction force. It means that the power to do is reduced than usual.

  Therefore, in the present embodiment, the motor A actively generates heat (intentional heat generation) by applying the d-axis current command value Id ref, and the motor A driving force decreases by limiting the q-axis current command value Iq ref. The operation reaction force is stabilized regardless of whether or not the temperature T of the speed reducer 26 is lower than the normal temperature.

  However, the operational reaction force is stable regardless of whether or not the temperature T of the speed reducer 26 is lower than the normal temperature only by the positive heat generation (intentional heat generation) of the motor A by the application of the d-axis current command value Id ref. It is possible to carry out the present invention in a mode that can be realized.

  That is, the portion of the computer 42 that executes S35 constitutes the operation reaction force control gain calculation unit 40c in FIG.

  Thereafter, the process returns to S32 in FIG. 6 and the execution of steps S32 to S35 is repeated until the temperature T becomes equal to or higher than the threshold value Tth.

  If the temperature T is equal to or higher than the threshold value Tth, the determination in S33 is NO, and in S36, the d-axis current command value Id ref is decreased to 0, whereby the intentional heating of the motor A is terminated. . Thereafter, in S37, the command value α ref of the operation reaction force control gain α is set to 1, thereby ending the reduction of the operation reaction force by limiting the q-axis current command value Id ref. This completes one execution of the steering characteristic stabilization program.

  As described above, the case where the ignition switch 51a is immediately after being turned ON by the driver has been described. However, when the ignition switch 51a is not immediately after that, the determination of S1 is NO and the steering characteristics are stabilized through the execution of S36 and S37. A single execution of the program ends.

  As shown in FIG. 2, in the steered portion 20, the left and right wheels 12, 12 are steered by a rack and pinion method. The left and right wheels 12 and 12 are connected to both ends of the rack shaft 56 through the tie rods 52 and 52, respectively. A rack 60 is formed on the rack shaft 56, and a pinion 62 is engaged with the rack 60. The rack 60 and the pinion 62 constitute a motion transmission mechanism 64 that transmits motion to each other by a gear.

  A motor B and a motor C are mounted coaxially on the rack shaft 56. These motors B and C are mounted to displace the rack shaft 56 in the axial direction. These motors B and C are provided with a common rotor 66, and the rotational motion of the rotor 66 is converted into linear motion by a ball screw mechanism 68 as a motion conversion mechanism and transmitted to the rack shaft 56. It is like that. Each motor B and C is equipped with a relative angle sensor (for example, a resolver sensor) 70 that detects a relative rotation angle as a relative angle.

  A pinion shaft 72 extends coaxially from the pinion 62, and a motor D is mechanically linked to the pinion shaft 72 via a speed reducer (also a booster mechanism) 74.

  In the present embodiment, the speed reducer 74 is configured such that the wheel gear 76 and the pinion gear 78 mesh non-coaxially, as with the speed reducer 26. The wheel gear 76 is coaxially attached to the pinion shaft 72 so as to be integrally rotatable, while the pinion gear 78 is coaxially attached to a rotor (not shown) of the motor D so as to be integrally rotatable.

  The pinion shaft 72 is further provided with an absolute angle sensor 80 that detects an absolute angle that is an absolute rotation angle of the pinion shaft 72. The definition of absolute angle is the same as the above definition.

  The motors B, C, D, the two relative angle sensors 70, 70 and the absolute angle sensor 80 are commonly connected to the controller 40 together with the motor A and the absolute angle sensor 34. As shown in FIG. 3, the ROM 46 stores a steering control program that is executed by the CPU 44 in order to control the motors B, C, and D to control the steering angles of the left and right wheels 12 and 12. The steering control program includes a motor B control routine for controlling the motor B according to its electrical angle, and a motor C control routine for controlling the motor C according to its electrical angle, as in the control of the motor A. And a motor D control routine for controlling the motor D according to its electrical angle.

  As is clear from the above description, in the present embodiment, the temperature T being lower than the threshold value Tth constitutes an example of the “satisfaction condition at low temperature” in the item (2), and the temperature sensor 41 is An example of the “temperature sensor” in the item (3) is configured, and the reduction gear 26 configures an example of the “heated part” in the item (4).

  Furthermore, in the present embodiment, the ignition switch 51a being turned ON by the driver constitutes an example of the “establishment condition at the start of travel” in the above section (5), and the ignition switch 51a is configured as described in (6). This constitutes an example of the “travel start switch” in the section.

  Further, in the present embodiment, the steering wheel 22 constitutes an example of the “operation member” in the item (7), and the motor A constitutes an example of the “operation reaction force motor” in the item. . Further, the motor A constitutes an example of the “motor” in the item (10), and the portion of the computer 42 that executes S6 and S7 in FIG. 5 is the “drive current supply unit in the item (11) or (12)”. "Is an example.

  Next, a second embodiment of the present invention will be described. However, since this embodiment has many elements in common with the first embodiment, only different elements will be described in detail, and the common elements will be described in detail using the same reference numerals or names. Is omitted.

  In the present embodiment, as in the first embodiment, the speed reducer 26 is heated by the intentional heat generation of the motor A during the period when the temperature T of the speed reducer 26 is lower than the threshold value Tth.

  However, unlike the first embodiment, traveling of the vehicle is prohibited during a period until the temperature T rises to the threshold value Tth (for example, a period shorter than 1 minute, such as 30 seconds). This eliminates the need for the driver to perform a steering operation, so that the driver does not have to feel the uncomfortable feeling that the steering feeling changes while the vehicle is traveling.

  Therefore, in the present embodiment, it is not essential to change the operation reaction force control gain α to a value different from the normal value during the period until the temperature T rises to the threshold value Tth.

  FIG. 10 conceptually shows in a flowchart the contents of the steering characteristic stabilization program in the steering apparatus according to the present embodiment. Hereinafter, although the content of this steering characteristic stabilization program is demonstrated concretely, the step which is common in the step in the steering characteristic stabilization program in 1st Embodiment is demonstrated easily.

  In the steering characteristic stabilization program in the present embodiment, first, in S51, it is determined whether or not it is immediately after the ignition switch 51a is turned ON by the driver, similarly to S31 in FIG. If it is assumed that it is immediately after this time, the determination is YES, and the temperature T of the speed reducer 26 is detected in S52 as in S32 in FIG.

  If it is assumed that the detected temperature T is lower than the threshold value Tth this time, the determination in S53 is YES, and in S54, the d-axis current command value Id ref is determined in the same manner as S34 in FIG. The Thereafter, in S55, the start of the vehicle is prohibited. For example, an operation for starting by the driver (for example, for example, in a state where the driver is visually or audibly informed that the vehicle is prohibited from starting). Brake release operation, accelerator operation, etc.) are invalidated.

  Thereafter, the process returns to S52, and the execution of steps S52 to S55 is repeated until the temperature T rises to the threshold value Tth or higher.

  If temperature T rises above threshold value Tth, the determination in S53 is NO, and d-axis current command value Id ref is decreased to 0 in S56, and then vehicle start is permitted in S57.

  This completes one execution of the steering characteristic stabilization program.

  As is apparent from the above description, in the present embodiment, the portion of the computer 42 that executes S55 in FIG. 10 constitutes an example of the “vehicle travel prohibition portion” in the section (14), and the temperature T is reduced. The rise to the threshold value Tth or more constitutes an example of the “satisfaction condition at the time of temperature rise” in the same term.

  Next, a third embodiment of the present invention will be described. However, since this embodiment differs from the first embodiment only in the operation unit and is common to other elements, only the different elements will be described in detail, and the same reference numerals or names are used for the common elements. Therefore, the detailed description is omitted.

  As shown in FIG. 11, in the present embodiment, the operation unit 110 is configured to redundantly include two motors X and Y. The motors X and Y are connected to a common speed reducer 114 via a common rotor (not shown). An operation shaft 24 is connected to the speed reducer 114, and the rotation of the motors X and Y is decelerated and transmitted to the steering wheel 22 via the operation shaft 24. The motors X and Y are electrically connected to the controller 40 via respective drivers 36 and 36.

  As shown in FIG. 11, similarly to the first embodiment, the temperature sensor 41 is associated with the speed reducer 114, and the detected value of the temperature T of the speed reducer 114 is supplied to the controller 40. The operation angle of the steering wheel 22 is detected by the operation angle sensor 118. The detected operation angle is supplied to the controller 40 as the electrical angle of each motor X, Y.

  In the present embodiment, both the motors X and Y are not controlled to intentionally generate heat in the same manner as the motor A in the first embodiment. In the present embodiment, the same control as the control of the motor A is performed only for the two motors X and Y that are close to the speed reducer 114. Of these two motors X and Y, those that are in positions where heat can be efficiently transmitted by the speed reducer 114 are designed to generate heat intentionally.

  As is clear from the above description, in the present embodiment, the speed reducer 114 constitutes an example of the “transmission device” in the item (13), and the controller 40 constitutes an example of the “controller” in the item. It is.

  As described above, some of the embodiments of the present invention have been described in detail with reference to the drawings. However, these are merely examples, and those skilled in the art, including the aspect described in the section of [Means for Solving the Problems], described above. It is possible to implement the present invention in other forms in which various modifications and improvements are made based on the knowledge.

It is a systematic diagram which shows the operation part 10 among the steering apparatuses according to 1st Embodiment of this invention. It is a systematic diagram which shows the steering part 20 among the said steering apparatuses. It is a cross-sectional view which shows a part of motor A in FIG. FIG. 3 is a block diagram conceptually showing the configuration of a controller 40 in FIGS. 1 and 2. 5 is a flowchart conceptually showing the contents of an operation reaction force control program in FIG. 4. 5 is a flowchart conceptually showing the contents of a steering characteristic stabilization program in FIG. It is a functional block diagram which shows the controller of FIG. It is a graph which shows an example of the relationship between the temperature T in the steering characteristic stabilization program of FIG. 6, and d-axis current command value Id ref. 7 is a graph showing an example of a relationship between a temperature T and a command value α ref of an operation reaction force control gain α in the steering characteristic stabilization program of FIG. 6. It is a flowchart which represents notionally the content of the steering characteristic stabilization program performed by the computer of the controller 40 in the steering device according to 2nd Embodiment of this invention. It is a systematic diagram which shows the operation part 110 among the steering apparatuses according to 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10,110 Operation part 22 Steering wheel 24 Operation shaft 26,114 Reduction gear 27 Stator 28 Rotor 29 Coil 30 Permanent magnet 40 Controller 41 Temperature sensor 51a Ignition switch A, B, C, D, E, F, X, Y Motor

Claims (10)

A steering device for steering a vehicle by turning wheels in accordance with a steering operation of a driver in the vehicle,
A motor having a stator and a mover;
A moving member moved in relation to the steering;
A transmission device for transmitting the movement of the mover to the movement member;
A controller for controlling a supply current to the motor, and when a predetermined condition is satisfied, supplies a heat generation current for the motor to generate heat without the movement of the mover. Steering devices including things.   The steering apparatus according to claim 1, wherein the condition includes a low-temperature condition that is established when a temperature of a heated portion to be heated by heat generation of the motor of the steering apparatus is equal to or lower than a set temperature.   The drive resistance that the transmission device needs to beat to drive the transmission device is greater at the low temperature of the transmission device than at the high temperature, and the heated portion is the transmission device The steering apparatus according to claim 2.   The steering apparatus according to any one of claims 1 to 3, wherein the condition includes a travel start time satisfaction condition that is satisfied when a series of travels of the vehicle is started.   Furthermore, an operation member that is operated by a driver includes an operation member that drives the motion member so that the motor acts on the driver via the operation member with an operation reaction force to the operation of the operation member by the driver. The steering apparatus according to any one of claims 1 to 4, comprising a reaction force motor. In the motor, a permanent magnet is mounted on one of the stator and the mover, and a coil is mounted on the other, respectively, and the direction parallel to the magnetization direction of the permanent magnet is in the direction perpendicular to the d axis. Are q-axis set respectively.
The steering apparatus according to any one of claims 1 to 5, wherein the heat generating current is a current that flows through the motor only in a d-axis direction out of the d-axis direction and the q-axis direction.   The controller includes a drive current supply unit that supplies a drive current for driving the mover to the motor in parallel with supplying the heat generation current to the motor during a steering operation of the driver. The steering apparatus according to any one of claims 1 to 6.   Furthermore, an operation member that is operated by a driver is included, and when the driving current supply unit supplies the heat generation current to the motor, an operation reaction force to the operation of the operation member by the driver is higher than when not supplied. The steering apparatus according to claim 7, wherein the drive current is changed so that the amount generated by the motor is reduced.   The drive resistance that the transmission device needs to beat to drive the transmission device is greater at a low temperature of the transmission device at a high temperature, and the motor is operatively connected to the transmission device. The steering apparatus according to claim 1, wherein a plurality of the motors are provided in association with each other, and the controller supplies the heat generation current to a motor closest to the transmission device among the plurality of motors. The said controller contains the driving | running | working start prohibition part which prohibits the driving | running | working start of the said vehicle until the temperature rising condition satisfaction condition satisfied when the temperature of the said to-be-heated part rises more than preset temperature is satisfied. The steering apparatus as described in.

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